Scientists reprogram body’s own cells to kill cancer, HIV

In a pair of papers published in the journal Cell Stem Cell, researchers from two separate Japanese universities have successfully used a new technique to reprogram the body’s own immune cells to seek out and destroy cancer cells and HIV. The researchers hope that this technique can be developed into a practical therapy for cancer, HIV and other hard-to-treat conditions. Ideally such a therapy would be free of side effects, as it would make use of the body’s own innate immune capability.

The body naturally produces a type of immune cell, killer T lymphocytes, that possesses the ability to kill not only viral and bacterial invaders, but also to destroy certain compromised cells of the body itself, such as cancerous cells or those infected with the herpes virus. Unfortunately, killer T lymphocytes are normally very short-lived, and often fail to destroy tumors before expiring themselves (this explains why, in spite of our immune systems, we still sometimes develop cancer). Experimental therapies seeking to use the body’s own T lymphocytes to fight cancer have also often failed due to the cells’ short lifespan.

In the new studies, researchers used a group of compounds known as “Yamanaka factors,” which cause cells to revert into their earlier, undifferentiated stem cell form. These stem cells are of a variety known as induced pluripotent stem cells (iPS cells), with “pluripotent” meaning that the stem cells are able to differentiate into more than one type of cell.

The researchers then allowed the iPS cells to re-differentiate back into killler T lymphocytes. They found that this “reboot” produced killer T lympocytes with much longer lifespans.

Rebooting the killer T cells

In one study, researchers from the RIKEN Research Centre for Allergy and Immunology created iPS cells from killer T lymphocytes that had developed to target melanoma skin tumors. The iPS cells then differentiated back into T lymphocytes that, strikingly, were not only able to recognize the MART-1 protein characteristic of melanoma and to produce to the anti-tumor chemical interferon ?, but also were much longer-lived than natural T lymphocytes, and remained active as anti-cancer agents for their entire extended lifespan.